Bump sidekiq-unique-jobs from 5.0.10 to 6.0.8 (#9801)

Bumps [sidekiq-unique-jobs](https://github.com/mhenrixon/sidekiq-unique-jobs) from 5.0.10 to 6.0.8.
- [Release notes](https://github.com/mhenrixon/sidekiq-unique-jobs/releases)
- [Changelog](https://github.com/mhenrixon/sidekiq-unique-jobs/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mhenrixon/sidekiq-unique-jobs/compare/v5.0.10...v6.0.8

)

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